The present invention relates to the art of rotary machines and, more particularly, to a balancing member assembly for a rotating component in a rotary machine.
In the manufacture of rotating machines, such as turbomachinery, final balancing of rotating components is an essential and important step. In addition to final balancing after manufacture, periodic re-balancing of the rotating component is necessary in order to ensure proper operation and long operational life. Balancing is typically achieved by adding or removing weights to the rotating component, e.g., rotor, to compensate for deviations in rotor straightness and components mounted to the rotor, such as buckets and covers, or to lower vibration levels at which the turbomachine is operating.
The weights are typically mounted in weight grooves or openings formed in the rotor body. Weight grooves intended for use during manufacture of the turbomachine typically have a T-shaped or dovetail cross-section. Other balance weights include threaded plugs located along the rotor body. Balance weights are typically one to live times longer than an air gap, i.e., the gap that exists between the rotor body and a stator, or an entrance gap, i.e., the gap that provides access to the air gap of a rotating machine. Thus, changing weights with the rotor installed in the turbomachine is not possible. Therefore, the rotor must be removed, transported to a balance facility, balanced and returned to service. This process can take as much as 2-3 weeks, adding considerably to machine down lime. A power plant, for example, can loose significant revenue each day the turbomachine is out of service.